Aphids are a sure sign of spring and with aphids come a host of other insects that depend on them for food.
Take this insect near the bright orange-yellow oleander aphids on the rush milkweed. It looks a bit like a wasp with its ultra-thin "waist", but its actually a fly, becuase it has two wings rather than four.
It is Dioprosopa clavata, a type of flower fly (family Syrphidae). Another common name is aphid fly, because its larvae eat aphids. In fact, if you look up a bit on the stem to the right of the fly, there's an older flower fly larva.
The larva will pupate soon and become an adult aphid fly, so the cycle will continue. It is the life cycle of a family of specialist flies, based entirely on a few aphids on a milkweed plant.